English Reference

Word

act

US/ˈækt/

UK/ˈækt/

Definitions

01to do something

A1 · Beginner

v. to take action or do something for a specific reason.

v. to take action or exert energy in order to achieve a specific result. Often used intransitively.

“The police had to act quickly to stop the thief from escaping.”

“The emergency services must act decisively when a natural disaster strikes to minimize the loss of life and property.”

Antonyms

02theatre/film

A2 · Elementary Theater

v. to perform a part in a play, movie, or television show.

v. to perform a fictional role in a dramatic production. Can be used transitively with a role as the object or intransitively.

“She has wanted to act in a Hollywood movie since she was a child.”

“He was chosen to act the part of the protagonist because of his ability to convey complex emotions without speaking.”

03to behave

B1 · Intermediate

v. to behave in a particular way.

v. to conduct oneself or behave in a specified manner, often temporarily or falsely.

“Stop acting like a child and help me clean the kitchen.”

“The suspect began acting suspiciously as soon as the investigators mentioned the missing documents.”

Synonyms

04a deed or thing done

A2 · Elementary Countable noun

n. something that someone does.

n. a single thing done; a deed or action.

“Giving her seat to the elderly man was a kind act.”

“The charity described the donation as a selfless act of generosity that would fund the project for a year.”

Synonyms

05a law

B2 · Upper Intermediate Countable noun Law Formal

n. a law that has been officially passed by a government.

n. a formal decision or law passed by a legislative body. Often capitalized when referring to a specific law.

“The new Act of Parliament will change how taxes are collected.”

“The Clean Air Act was introduced to regulate industrial emissions and improve public health in urban areas.”

Synonyms

06part of a play

B1 · Intermediate Countable noun Theater

n. one of the main parts that a play or opera is divided into.

n. a major division of a dramatic work, such as a play, ballet, or opera.

“The hero doesn't appear until the second act of the play.”

“The tension builds throughout the first act, culminating in a dramatic confrontation just before the intermission.”

Synonyms

07a performance or show

B1 · Intermediate Countable noun Theater

n. a short performance or a person/group that performs as part of a larger show.

n. a short performance or one of several performances in a variety show or circus.

“The circus had a very funny clown act that the children loved.”

“The festival organizers are still looking for a headline act to close the main stage on Sunday night.”

Collocations

Common phrases and expressions where native English speakers use the word “act” in context.

Verb

01. independently act

“Young children often want to independently act without help from their parents.”

adv + verb

02. perform act

“The magician will perform an act that involves disappearing from the stage.”

verb + noun

Noun

03. act require

“The new Act requires all businesses to reduce their plastic waste.”

noun + verb

Word family

Related words

Idioms

Domains

LawMathematics

This entry

Exam level
CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B1 PreliminaryIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.4.0–5.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 3.0–3.544–71TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.550–784
Frequency
Very common
Level
B1 · IntermediateOxford
Updated

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English Reference